Smart phones and other cellular devices are ubiquitous. People use these devices for both business and personal use. Many cellular devices include both voice call capabilities and data capabilities such as, for example, web browsing and e-mail. These services are generally billed to consumers in plans that may include a predetermined number of minutes, megabytes (MB) or gigabytes (GB) of data, and/or short messaging service (SMS, or text) messages.
Cellular devices can also be billed on a pre-pay or post-pay basis. As the name implies, pre-pay billing requires that the user buy a block of minutes and/or data in advance. When all (or nearly all) of the minutes or data is used, the user must purchase additional minutes and/or data. In some cases, the user may receive a text message or other notification that he is almost out of minutes and/or data. Post-pay customers, on the other hand, are billed for the minutes and/or data used during consecutive billing periods.
Cellular carriers sometimes associated their user equipment (UEs) to their network, or “SIMLock” their devices. This is at least in part because cellular carriers are not solely in the business of selling UEs, but rather tend to sell both UEs and UE related services. Often carriers sell UEs below cost, or subsidized UEs, for example, to attract new customers or retain existing customers. As a result, it is important for carriers to have their UEs locked to their network and/or to be able to apply additional restrictions, as necessary.
Currently these restrictions, or “SIM locking criteria” are hardcoded into the device modem with no ready mechanism to securely update that locking criteria. These criteria can currently only be changed using hardware solutions, such as device re-flashing. This approach presents at least two issues. The first is that the carrier has to decide what device locking rules will be applied at the outset (e.g. restricting a UE to a particular network). These rules are then given to the device manufacturer for hardcoding, for example, and thus must be decided on effectively making the decision permanent. The second issue is that the chosen locking rules cannot now be easily updated without reflashing, for example, which may require returning the UE to the manufacturer, among other things.
As a result, to minimize the number of different devices (e.g., SKUs or variants) that the carrier has to stock, the carrier is forced to choose very generic locking rules. In many cases, the carrier may lock the UE at the country and network level (e.g., MCC/MNC). While this has the advantage of keeping the number of available device variants low—and the costs associated with stocking a supporting each variant—it makes it also provides little opportunity for the carrier to use different, or stricter, locking rules on the UEs once they have been placed in service.